Selective signaling system.



0. M. LEIGH.

SELEGTIVE SIGNALING SYSTEM.

APPLIOATION FILED MAY 3, 1901.

1,002,71 3, Patented Sept. 5,1911.

UNITED STATES PATENT onrrcn.

OSCAR M. LEIGH, OF CHICAGO, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS, OF ONE-- THIRD TO J'. G. IHMSEN AND TWO-THIRDS TO 1?. C. BURNS, BOTH OF CHICAGO,

ILLINOIS.

SELECTIVE SIGNALING SYSTEM.

Specification of Letters Patent.

Patented Sept. 5, 1911 Application filed May '3, 1901. Serial No. 58,647.

To all whom it may concern:

Be it known that I, OSCAR M. LEIGH, citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented a certain new and useful. Improvement in Selective Signaling Systems, of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawings, forming a part of this specification.

My invention relates to selective signaling or calling apparatus, and has for its object the provision of improved means for trans mitting selective signals to a plurality of stations, a signal transmitted to one station not affecting signals at other stations.

My invention is particularly applicable to party line telephone systems, and has for its object the provision of an improved system of non-interfering signal bells or ringers whereby ity is possible to convey selective signals over such a telephone system to operate any desired substation signal without disturbing other signals of the party line.

My invention is primarily designed to overcome objections and insufiiciencies of systems of the prior art designed to accomthereon. The remaining signals of the line' are then preferably so constructed as to be responsive to an alternating current of a frequency which does not operate the aforesaid signals.

Generally stated, therefore, my invention comprises, in the preferred embodimentthereof, four signal receiving instruments adapted for association with the tivo limbs of a metallic circuit, and. a common return which may preferably be a ground return, thus dividing the signals into two groups. The signal receiving devices are then. preferably provided with windings which act. diiterentially when energized by an alter hating current of a certain frequency, thereby preventing operation thereof, and which provision of a plurality of sig-.

cies are adapted to operate windings do not act'in such manner .When a current of different frequency is impressed thereon, whereby the signals may be actuated. The windings are so associated with reactive means that the ratio of the currents in the two windings vary when currents of different electrical character such as currents of difierent frequency, are im pressed thereon.

It will be seen, therefore, that my invention contemplates broadly the use of reactive means, such as impedance coils or condensers, for preventing false signaling in a party line system in Which the ringing circuits are non-resonant for the different frequencies'that are employed in selectively signaling the party line subscribers.

I will describe my invention more in de tail by reference to the accompanying drawing illustrating one embodiment thereof, in which- Figure 1 is a diagrammatic view of a. telephone system built in accordance with my invention; Fig. 2 is a diagrammatic View of the arrangement of circuits of one of my improved signal receiving devices; and Fig. 3 is a similar view of another of my improved signal receiving devices.

Like characters of reference indicate like parts throughout the different figures.

I have illustrated a telephone party line system comprising the substations 1, 2-, 3, 4. associated with the limbs 5, 6 of a metallic circuitterminating at the in a spring jack 7. I have also shown a single metallic subscribers telephone set 8, core nected at the exchange to a spring jack 9'. The spring jacks are shown as provided with two back contacts for disconnecting the hat-- tery 10 and the line signals 11, 1% respectively from th jacks when. plugs are in serted the-rein Suitable instrumentaiities are provided at the exchange to effect interconnection between the telephone fines and to supply current thereto. The stations 1, 2, 3 and 4 of the party line are each provided with a transmitter 13, a receiver i l, and are also respectively provided with selective callsi nal. devices 1'5, 16, 17 and 18. The selective ringers or calling devices 15 and 1? are connected liietwcen the limb 5 and ground,

and. the similar signals 16 and 1.8 between the limb 6 and ground.

Alternating currents of different requiem one or the other,

15and 16 responsive to .an alternating curof the aforesaid signal, receivingdevicegand to this end I have provided at the exchange two generators 19 and 2 0, the generator 20 being adapted to supply an alternating cur; rent preferably of a frequencytwiccas great as that supplied by the generator 19, said frequencies being desirably 24L and 12. A four-way ringing key provided with foursets :of springs 21, 22, 23 and 2a is provided at the exchange to associate either generator in circuit with either limb 5 or G and the ground. Plugs 25, 26 effect connection be.- tween the jacks 7 "and 9, and supply current to theli-nes from the battery 10througl'1 an impedance coil 27 and-a clearing-out relay 2&" 'Su table operators telephone set such keys are.,prov1ded in the cord circuit.

Signalfreceiying devices and 116 are adapted to operate on the high frequency current, and

signals 17 and 18 are adapted to operateon the lowfrequency current. In'accordance herewith, key2l is adapted to associate gen erator 20 between limb'li and-the ground to operate signal receiving device 15; key 22 is adapted to associate generator 20 between limb (land the ground to operate signal receiving device 16; keys 23 and 24 in like manner associate generator 19 with the limbs to respectively operate signal receiving (16- vices 17- and 18.

'In-o'rder to have signal receiving devices rent of high frequency and unresponsive to a current of low frequency, I provide two windings 2 9.and 3O upon a magnetic core, said core acting inductively upon an.armature for operating a signalbcll or ringer. The armature is also preferably polarized. The windings 29 and 3 0 are d-ifierentially wound so that when" equally energized they may neutralize each others magnetizing effect. flne COllS 29 and 30 of each signal rece vlng device are connected'fm parallel C11:-

. cuits between the respective limb of the metallic circuitand thefground. I include an impedance (1011131 ands condenser 32 in series with'cach coil 3o of the devices 15 and 16, the impedance coil tendingto, neutralize the 'efte'ctof the condenser on a high frequency, this case on a. frequency of 24 'A rangement' is shown in diagram, in Fig. 3,

lVhen a-low'frequency isflimprcssed on: the "parallel circuits of th'e device, (12, for,

" insta ce) "then the impedance of: coil 31 is low aiidthe impedance of j condens'er 32 high, so "that the impedance of they parallel "circuit including'said coil 31 is very nearly equal tothe impedance ofthe circuit includmg condenser 33. Currents of very nearly:

equal strength will thus pass through the two circuits, and as coils 29. and.3O are dif-j impedance 'ofthe'condcnsers 32 and 33 is rents of high frequency (24, in this case),

r I in series with each; coil 29 of the devices-'15 and 16, said con denser preferably having a capacity atriflc greaterthan that of condenser 32. Thisiar;

ferentially Wound no actuation of said devices 1510i, 16 is secured. If, however, a current of high frequency (24, for instance is impressed on either device 15 or 16, the

materially less than for, the lower frequency, and. theimpedance of the coil 31 correspondingly increased; but as the impedance of the coil 31 tends to neutralize the effect of condenser 32, on the higher frequency, the circuit contannng coil 30 receives a much larger amount of current than the circuit including coil 29, which latter is in series with an impedance in the form of condenser 33. As an unequal amount of current thus traverses the coils 30 and 29, on the highfrequency, an actuation of the signal bell is secured. It will thus be secnithat devices 15 and 16 are responsive to alternating curandunresponsivc to currents of low frequency, (such as 12).

By the terms. high frequency and low' frequency, as used in connection with the embodiment of the invention herein shown,

I mean simply to distinguish between two frequencies the relative, and not actual,

values of which enter into consideration in the operation of the present case. i

Signal receiving devices 17 and 18 are responsive to currents of low frequency and unresponsive to the currents of the high frc- To obtain this result 1;:

quency generator. again provide two differential co1ls,29 and,

.30 upon a suitable core, and'againinclude *Wllill each coil 30 an' impedance coil 31 and a condenser 32 which tend toneutralize on the. higher frequency ,(24). :NO condenser is included with the;coil 29 in this instance,

but the two signal circuits'are togethcriu:

cluded in series with a condenser 34, for the purpose to be set forth hereinafter. It will be scenthat the current of higher frequency tending,to neutralize the impedance of fcoil 31 and condenser 32, passes in equal amounts through coils 29 ,and 30, and thus does not operate the signal bell. "If, however, current of lower.v frequency 15 impressed'on the circuits of devices 17 and 18, the inductance, of the circuits including coils 30 is materially decreased and the imipedanceof the condenser greatly increased;

so that said circuit now has an impedance 30, andthe signal bell, willjbe operated at greatly in excess of, the circuit including; coil 29. considerably more current will, thus flow through ,coil 29 than through coil.

either station 3' or 4, depending upon whetherli mb 5 or 6 is included in circuit. 7

- By means of my invention I am enabled to so associate condensers with the signal re-" ceivmg dev ces that no current from the common battery 10can flow therethrough Condensers 32 and 33 are"'associated with the devices 15 'and 1 6, and condenser 34 ac-- which the windings distinguishing between :can be applied to the bells or signals suitable manner.

c'omplishes a like result for the devices 17 and 18.

While I have herein shown and particularly described one embodiment of my invention, .I do not wish to be limited to the precise construction and arrangement as herein shown and particularly described.

For the broader purpose of my invention, the means or provisions by which the signals or ringers at the substations distinguish bet-ween the different frequencies can be of any suitable character. Preferably, however, the reactive means ofat least one signal are adapted to distinguish or assist in the different frequencies. Obviously, the reactive means in any Preferably, smooth and uninterrupted alternating currents are employed, and the bells or signals arepolarized by permanent magnets,, as this combination I find gives the best and most satisfactory results.

It will be seen that reactive means are provided for preventing current of one frequency from ringing a. bell intended to be run by a currentof a different frequency. In tnis way, the different ringing or signaling curcuits are non-tuned in character, but

- at the same time an effective selectivity of signaling is secured.v The reactive means, of any suitable charactr r, prevent an operative flow of one f1 quency through the ringer intended to be rung by a difierent frequency. By the expression non-tuned, I mean that the ringing circuit of each bell or ringer is non-tuned relatively to the frequency by which the bell is rung. In other Words, there is no electrical resonance or tuning of the ringer circuits relatively to the different frequencies by which they are operated. In this way a certain frequency in passing through a ringer to operate that ringer does not traverse a circuit which is tuned relatively to that particular he quency. This is for the reason that in the ringing circuits .no attempt is made to so adjust the inductance and capacity as to attain resonance, or even to approximate such a condition. a

It will be understood, of course, that I do not limit myself to any particular frequen cies, or any particular capacity or resistance, as these ma be varied without departing from the spirit of my invention. Take, as an example, a system of this kind in which the condense s 3% are all of two inicrofarad capacity, while the condensers 32 and 33 are all of one inicrofarad capacity, in are all of five hundrcd ohms resistance, the windings 29 all' of fifteen hundred chins re. stance, and the impedance coils 31 all of one thousand ohms resistance, in which av current of 20 cycles, is employed for ringing low frequency bells.

1 however,

and in which a'current of cycles is used for the high frequency bells. In such case, the high frequency current passes in practically equal amounts through the parallel windings of the low frequency bells, thus preventing the same from ringing. The 20 cycle current, however, will pass in larger quantities through the winding 29 of the lowfrequency ringer, owing to the capacity included in the other part of the branch, and the said ringer will be operated. But when the frequency is increased to 60 cycles, keeping the voltage at 100 volts, the reactance of the condenser associated with the high frequency ringer will be only onethird of that which is true when a twenty cycle current is impressed upon the line. The impedance of the 1000 ohm coil is, ho. ever, three times as great. and, therefore, the current in the 1500 ohm winding of the high frequency ringer will be greatly increased over and above that in the 500 ohm wind.- ing. Also, the phase relation of the two currents in these parallel windings is greatly increased. It can be readily seen that when the two windings are connected differentially, when the currents are 180 out of phase, Therefore,

no neutralization will take place. the larger the angle of phase up to 180 the less the neutralization. Under these conditions, therefore, the said high frequency ringer can be made unresponsive to a 100 volt 2O cycle current; but it will respond readily, as explained, to the 100 volt 60 cycle current. It will also respond should the conditions remain the same, except that the iron in the impedance coil be increased enough to neutralize the capacity of the condenser in series therewith when a G0 cycle current is impressed upon. the line. In such case, it will be seen that a greater current will then flow through the 500 ohm winding of the high frequenqy ringer, and the latter can be made sensitive enough to ring under these conditions.

From the foregoing, it will be seen that only one ringer responds when any certain frequency is projected on to the line. More specifically considered, each ringing circuitincludes but a single ringer. In this way, only one signal results. from the of any particular current. The ringers constitute a signal receiving device, and the condensers and impedance coils are associated therewith, forming a signal receiving apparatus, in'the manner explained. Of the different frequencies which are actually used on the line, each ringer is adapted to respond to only one of them.- The high frequency ringer is, so connected with the line that it would respond to any higher frequency which might be thrown on ,the line. This is also true of the low this ringer would respond to any lower frequency which might be thrown on the line frequency ringer, as

' Each signal receiving means is, therefore,

low frequency ringer has its circuit non-tuned dependently for inclusion W thba id circuit" and 'respom" adapted to distinguish between the different frequencies'ivhich are actually used, so that the signaling is sclectivc,=and no false signaling occurs. The ringing or operatingcurcuit of each substation-is"non-tuned or non-resonant for the particular frequency by Which its allotted ringer or" signal receiving device is-operated.- The circuit of the high frequency ringer is non-tuned or non-resonant for the high frequency current which is actually eniployed,andfor any higher frequency. The

for the low, frequency current-Which is actu-,

allyirisedpand for any; lower frequency I}- am en'abled, tliereforc=,.to obtain the (lCSHGCl' selectivity of signaling by thc use of reactive D'lQtlllS'iD the circuits, 'but Ido not usc such :reactive means for-harinonically tuning the circuits that'is to say,-the circuits are not made resonant forthe difierent ringing currents. n

It Will be seen-that there isa'inain or line circ'uit, ainl a l ranch circuit to and through each substation. It will also be seen that each.substation and the ringer thereof has a path for ringing current which is nontuned-orinon-resonant for the particular' frequency to Which the Ill'l'Ql'ylS responsive, and by which the station can he signaled. Each ringer has'an operating Winding, and in addition thereto each ringer has a reactive shunt Windin serve the operating Winding thereof, and the other winding then becomes tlie'reactive shunt. In any. event, therefore, each ringer,

ringeris responsive.

'Ldo not limit myself "to the exact con struction or'ineth od of operation shown and described, as it obvious that various changes or modifications can be made,-- as by using-different" kinds of ringers, either tuned or non tuned, andi, by using the 'reac-- two means, such as impedance coils or condensers, or botli, at only one or more of the substat ons,instead ofat all of the substations' on the line,'-to preventfalse signaling in a systeminwhich the ringing circu'. s are non-tuned for the dlfi'erent frequencies, and

jy'vi-tl-iout in any Way departing from the spirit,ofunyunvention.

I claim asin'iy' invention:

la lnw'a party line system, the comb ina tion'with an electric'ci rcuihof meansforinnnprcs. ng alternatlng currents of different selectively thereon ,a J

signalj th'e difierent subscribers al 're.ceiving device adapted quen a second signal receiving 'device rerents of different frequencies upon said cirlVhichever indingof the ringer Cflll'lGS'd'llQ most current will ficqi'lelricy' upon said circuit, to

frequencies, and electro magnetic means associated with the second signal receiving device for preventing actuation thereof by currents of afrequency vhich are adapted to I,

operate the first aforesaid device and branch circuits for the different stations of said;

signal receiving devices, each station circuit. being non-tuned or non-resonant for the] particular frequency by which its allotted signal receiving device is operated. v

2. In a party line system, the combination with an electric circuit, of means for: independently impressingalternating cur cuil', to' selectively signal the ,diifcrentsubs fi scribers thereon, a signal, receiving device adapted for incljusionwith said circuit and responsive to an alternating current of a certain frequency, a second signal l'GCGlV':

ing device responsive to alternating currents of a different frequency, electro-magnetic' means associated with the first signal receiving device for preventing actuation thereof bycurrents of a frequency which are adapted to-operate the second aforesaid device, and reactive means associated with the 3.. :second signal receiving device to prevent actuation thereof by currents of a frequency :1; which are adapted to operate the first aforesaid device and branch circuits for the (hf-- ferent stations of said signal receivingd vices, each station circuit being non-tuned or nona'esonant for the particular fre- 'quency by which its allotted signal receiving" device is operated. I I v In aparty line system, the combination \vitlran electric circuit, of means for im-i. f pressing alternating currents of diii'erent'i' (frequencies independently upon said circuit,

thereon, a signal receiving device adapted fOl"111Cll1S1OI1 With said circuit, reactive devicewhereby said signal receiving devicef tain frequency, asecond signal receiving device comprising electronnagnetic means for operating the signaL-ahd reactive means for preventing the operation of the said eleetro niagnetic means upon energization of said reactive means, whereby said second signal" receiving device is responsive to alternating "currents of different frequency. 7 A subseribe'rs telephone substation signal 'receiving device comprising...electro-- magnetic means for operating a signal, in combination with reactive means for pref venting the operat-ion of said signal when" alternating current of a given frequency is impressed on said electromagnetic means r0 operatively energize the same and means for supplying alternating electric currents of" I different frequency. 7

5; .A subs'cribers telephone substation" signal receiving device'comprising electro- J to selectively signal the different subscribers lis responsive to alternating currents of oern means in circuit with said signal receiving magnetic means for operating a signal, in combination with reactive means inductively associated with said electro-magnetic means for preventing the operation of said signal when alternating current 'of a given frequency is impressed on said means, and a non-tuned energizing circuit for said electromagnetic means.

6. A subscrihers telephone substation signal receiving device comprising electroma netic means for o eratin a si nal. elecb r b tric circuits for controlling the operation of said electromagnetic means and reactive means associated with said circuits whereby the relative impedance of said circuits is varied when alternating currents of different frequencies are impressed thereon thereby to prevent the operation of said signal upon an operative. energization of one of saidcircuits and means for supplying alternating electric currents of different frequ r 8. A subscribers telephone substation signal receiving device comprising electromagnetic means for operating a signal, electric energizing circuits for controlling the operation of said electromagnetic means and inductively associated therewith, and reactive means associated with said circuits whereby the relative impedance of said circuits is varied when alternatin currents of different frequencies are 1mpressed thereon.

9. A subscribers -t-elephone substation signal receiving device having'difi'erential windings, and reactive means associated therewith, said react-ivemeans permitting an operative energizing*of bot-h of said windings when current ot 'certain frequency is impressed thereon, and permitting of an operative energization of but one winding upon impression of current of different frequencies.

lOfln a party-line telephone system, the combination of an electric circuit, a plurality of parallel branches in said circuit,a signal associated with. each branch, re-activc means for each branch, the reactive means'of the different branches being differently adjusted, and the reactive means of each station being thereby adapted to prevent an effective passage through its allotted signal of all currents except those intended and adapted toccause the operation of such. signal, and means for projecting alternating currents of different frequency on to said circuit for the urpose of selectively operating said signa s, each branch leading through a different tion and being non-tuned or non-resonantfor the particular frequency by which its allotted signal is operated. i

11. In a party-line telephone system, the combination of an electric circuit, a signalsubsta.

receiving apparatus connected with said circuit and responsive to alternating currents of a predetermined frequency, and to any h1gher frequencies that might be used,

.other signal-receiving apparatus connected with said circuit and responsive to alternating currents of a predetermined frequency, and to any lower frequencies that might be used, means for projecting alternating currents of different frequencies upon said circuit for the purpose of selectively operating the signals included in said apparatus.

12. In a selective party-line telephone signaling system, the combination with an electric circuit, of means for impressing currents of different frequencies upon said circuit, a signal receiving device included in said circuitand responsive to a current of a certain frequency, said signal-receiving deyice comprising electro-magnetic means for operating a signal and a re-active shunt circuit inductively associated with said electro-magnetic means for preventing an operative actuation thereof when current ofa given frequency ,is impressed on said means andshunt circuit, a series of additional signal-receiving devices included in said circuit and responsive to currents of different frequency, and means associated with each of these additional signal-receiving devices for preventing actuation thereof by currents of a frequency which are adapted to operate the first mentioned signaling device. a

13. A party-line telephone signaling system comprising an electric circuit, means for impressing alternating currents ofdifferent frequencies independently upon said circuit, a signal-receiving device connected with said circuitand responsive to alternating currents of a certain frequency;af second signal-receiving device also associated with the same circuit and responsive to alternating currents of different frequency, and

reactive means associated with the second signal'receivmg device, for preventing actuation thereof by alternating currents of frequencies which areadapted to operate the first-aforesaid device, the different signal-receiving means being each adapted and designed independently of any signaling action of the other to perform its intended function of giving a signal to attract attention, and a branch circuit for the substation ircuitbeing non-tuned or non-resonant for lotted signail receiving device'is'operated.

{ a 14:. A-party-line 'telephone signaling sysf tein comprising an electric circuit, means for selectively"impressing alternating" currents Q of different frequencies upon said cii-cuit,a

I O circuit, reactive means associated with said signal-receiving deVlCG, whereby said signalreceiving device 18 responsive to alternating i nal receivingdevice comprising an electro- "'15 finagnet for operating the signal, and a re- 1' active circuit for preventing theloperation of'the said electromagnet' upon sufiicient energiiation of said reactive circuit, whereby the said last-mentioned signal-receiving de-,

2 vice is responsive to alternating currents of a second signal-receiving device comprising Q and reactive means 'for preventing the op- 23 erationof'the said electroinagnet upon en-r v ergization of said reactive means, whereby the said second signal-receiving device is responsive to alternating currents of a diff ferent frequency.

16. A party-line telephone signaling system comprising an electric circuit, means for impressing'alternating currents of dif- ,ferent frequencies independently upon said 5 circuit, a signal-receiving device connected 'ivith saidcircuit, reactive means in circuit with said Slgnfll-IQCOlVlIlg device, whereby I alternating currents of certain frequencies, i and a second signal receiving device coniprising a polarized electromagnet for operating the signal and reactive means for preventing-the operation of- -the said electroj currents of a difi'crent frequency. v

17; A party line telephone signaling sysa teni comprising an electr c Cl1CU1t,SO.111CC of- 6 current and'nicans for supply ng-and inifrequencics' independently cuit, a signal-receiving device connected with said circuit and rcsponsivcto alternating current of a certain frequency, a second of each signal receiving device,'- each stat-ion f the particular frequency by which its al-' signal-receiving device, connected with said currents of certain frequencies, a'secondsiga different frequency together with means alternating currents of certain frequencies,

an electroniiagnet for operating the signal,

( said signal-receiving dev ce is responsive to magnet upon 'energization of said reactive means, whereby the said second signal-re ceiving device is responsive to alternating pressing alternating ciiiri'ents' of I di i'fercnt upon said cirsignal-receiving device responsive to alternating currents of a different frequency,

and reactive means associated with the second signal-receiving device, for preventing the actuation thereof by alternating currents of a frequency which are ada ted to operate the first-aforesaid device, he different signal-receivin means being each adapted and designed independently of: any signaling action of the other to perform its intended function of giving a signal'to attractattention, and a branch circuit for the substation of each: signal receiving device,

each station'ci'rcuit beingnon-tunedor noin resonantfor the particular frequency by which its allotted signal receiving device is operated.

18. A party-line telephone signaling sys tern comprising an electric circuit, source of current, means for impressing alternating currents of difi'erent i'frcquencies independently upon said circuit, a signal-receiving device connected Withsaid circuit and responsiveto alternating current-of a certain frequency, a, second'signal-receiving d'evice responsive to alternating currentsof a differentfreq'uency, said last-nieu'tioi'i'ed signah receiving device including a shunt-circuit for precluding the actuation thereof by alternating currents of frequencies which are adapted to operate the firstaforesaid device.

19, A party-line telephone electric; signaling system. comprising a c rcuit having a plurali=ty of parallel non-tuned .i'eactive signaling branches, there being a suitable trans lating device allotted to cachbranch, and means for projecting vibratory currents of different frequencies onto said circuinsaid means and reactive branches being adapted, by reason of the different degrees of iinpedance offered by the branches to the different currents, to conjointly vary the relative current-flow through said translating devices, and each translating deyice being rcsponsive to its allot-ted frequency of current,

and to no other ofthe currents actually used, whereby the different currents may be used at will for selectively operating the different translating devices, and each; signaling branch being iion esonant for the frequency by which its allotted translating device is operated, the diil'erent signal-receiving means thus provided being each adapted and designed independently of any signaling action of the other to perform its intended function oi? giving a signal to attract attention.

20. A party-line telephone electric signaling system comprising a circuit having a plurality ;,of 4 parallel non-tuned ringing branches, with a reactive, shunt in each brnncln and means. for projecting vibratory currents of diilcrent frequencies upon said 1 circuit, there being a reactive signal-receiving apparatus allotted to each branch, each apparatus including a translating device, each signal-receiving apparatus being responsive to, its allotted frequency of cur-- rent, and to no other of the frequencies actually used, and'the reactive means of said apparatus and the *said means for project ing currents being adapted, by reason of the different degre s of impedance offered by the reactive means to the different currents, to conjointly vary the relative current-flow through said translating devices, whereby the different currents may be employed at will forselectively operating said devices, the different signal-receiving means being each adapted and designed independently of any signaling action of the other to perform its intended function of to attract attention.

21. A party-line telephone electric signaling system comprising signaltransmitting apparatus adapted for sending vibratory or fluctuating currents of different frcqucn -ies, and reactive signal-receiving apparatus suitably connected with said signal-transmitting appaf'atus, said signal-receiving apparatus including a plurality ofsignal-magnetsLand means whereby each magnet when sufficiently energized produces a signal, each signalmagnetbeing responsive to its allotted frequency of current, and to no other of the frequencies actually used, and the said transmitting and receiving apparatus being adapted, by reason of the different degrees of impedance offered by the receiving appa-.

ratus to intermittent currents of different frequency, to conjointly increase and decrease. the relative flow of current in the different magnets, whereby the different currents may be used to selectively produce the different signals, said signal-transmitting apparatus including a switching device having keys corresponding to the different magnets and signals. I

22. A party-line telephone elect-r10 signaling system comprising signabtransmitting apparatus adapted for sending alternating currents of different frequencies, reactive signal-receiving apparatus suitably connected with-said signal-transmitting apparatus, said signal-receiving apparatus in-v cluding a plurality of signal-magnets, and means whereby each magnet when sufficiently energized produces a signal, each signal-magnet'beingresponsive to its alloted frequency of current, and to no other current used, the transmitting and receiving apparatus thus provided being adapted, by reason of the different degrees of impedance offered by the receiving apparatus to vibratory currents of different frequencies,"to conjointly increase and decrease the relative flow of current in the different magnets, as the frequency of the currentchan'ges, whereby the different currents may be used to selectively produce the different signals, said giving a signal signal-transmitting apparatus including a switching device having keys corresponding to the different magnets and signals, the different signal-receiving means being each adapted and designed independently of any signaling action of the other to perform its intended function 0 giving a signal to attract attention.v

23. In a party-line telephone system, the combination of a telephone line, a plurality of substations located on said line, a branch circuit for each substation, an exchange or central station, all party-line subscribers of the exchange being divided into different classes, a plurality of alternating current generators located at the exchange or central station, adapted to supply ringing currents of different frequencies, one definite frequency for each distinct class of party-line subscribers, means for connecting tlie requisite generator with the line of any called party'line subscriber, to which such called subscriber b elongs, ringers at the party-line substations, suitable reactive means for preventing current 'of one frequency from operatively passing through the ringer designed for a different frequency. and a telephone for each ringer, located at the different substations on the line, one or more of said branch circuits being nonresonant for the current thereof is responsive. 24; In a party-line telephone system, the combination of a telephone line, a plurality of substations located on said line, each provided with a different character of call signal, but with similar common-battery telephone instruments, a branch circuit for each substation, a battery common to all of said telephone instruments, an alternating current generator hiiving a certain frequency for operating one of said signals, an alternating generator current having a different frequency for operating a signal which is not responsive to said first-mentioned :frequency, and reactive means for preventing current of one frequency from operatively according to the class,

to which the ringer passing through the call signal designed for means for supplying alternating signaling currents of differentfrequencies, one frequency for eachsubstation, means at the,

substations for distinguishing the talking current from the signaling. currents, and reactive means at one or more substations for distinguishing between the different signaling currents, circuit through one of said sub stations being non-resonant for the current,

by which the station issignaled.

26. The combination of a telephone line,

, frequency current, hut pcriuittingz natingycurrents of different frequencies, one l're'quency tor each substation, saidcircuits jgnigsliing between the different frequencies -;assi s t in distinguishing between the dilterent frequencies that are actually used on the line, whereby the signal of such circuit only esponds-to it's allotted frequency.

.; 281, The con'ibination of a telephone line, -a-.plurality of substations located, on said :wline, asignal for each substation, parallel wh suitable frequency, a' different, frequency ii signal thereof to assist ain distinguishing between the dillicrcnt frequencies that are actually used on the line, by rendcr'rnglthe said .one circuit non-resonant for the freqnency to which its signal is responsive, and suitable provisions by which the other sig- 0:: nals are equally elfective in distinguishing 4 "betiveen the dilterent frequencies, whereby frequency. V

' 29. In a telephone exchange system, the combination of a telephone line, a plur: lity of substations on said line, a ringer apparatus ateach substation, a plu 'alityof con: "stantly operating altcrna'ting current dynainosfor supplying altcri'iating ringing currents Of"(lllltfl'QllhiilliI'CljUUIIClCS, a 'dill'crent requ'ency' foreacli substation, means f or at 7 phone for-reach" substation,

,gc ot"a low frequency (Zlll'ltllllzqtf heringer thereof, and; another apparatus liaving reactive n eaii,

frequency current,

sagetot the said high trcquency- Ultl'lfllllht actuate the ringer thcreol, one of said branch circuits being HOII-IQSOIlHnl) for the current to which its ringer is'responsive, whereby 1 :having reactive shunts to assist in distin ,tliat'iare actually nsed on the line, whereby means .01 at least one circuit adapted to branch circuits for said signals, means for supplying alternating-ringing currents of for eachsignal, at least one of saidcircuits ehaving reactive means associated with the eachsignal' only responds to its allotted willapplying tliodill'erentcurrciitsto the telephoneline, and a branch circuit and tele-ci one said ringer apparatus having reactive nicansiior pre-, venting the passagetheretlirongli oil; a high the passtor a e "venting'i the passage.thcretlirougli of a low.

butpermitting the pas-;,

a' p lurality of substations on said line, a 'sigew nal'for eachsubst-ation, parallel circuits for said Signals, and means for supplying alter-l said currents of difierent frequency and said reacti've nieans cooperateto produce selective ringing on the line;

30. In iLtGlQPllOllQ exchange 'systei'n, the

combination of a telephone line, a plurality of substations on said line, a ringer ap 'iaratus ateach substation, 'dynainos for supplying alternating ringing currents of different frequencies, af difi'erent frequency for each substation, means for at Will applying the different currents to the telephone line, one said ringerapparatns having reactive means tor preventing' actuation of the low-frequency ringer thereof by high frequency current, and another s'aidringer apparatus having suitable means for preventing actuation of the high-frequency ringer thereof by low frequency current, the substation of the low frequency ringer having a branch circuit that is non-resonant for the current to which its ringer is responsive.

31,-In atelepli'one exchange system, the combination of a telephone line, a plurality of subscribers stations on saidline, a suitable ringer at each station, means for supplying alternating ringing currents of differcnt frequencies, one dill'erent frequency for each ringer, ringing circuits for said ringers, each circuit non-resonant for the current to'i'vhich its ringer is responsive, and means to, prevent current otone frequency from passing through the ringing ci'rcuitof a.v ringer designed, tor another frequency, to an objectionable degree. I q

'i'na telephone exchange systen'i, the con'ibination of a telephone line, a plurality of electric bells or ringers normally con- .nectcd "therewith, parallel. ringing circuits for said bells or ringers, eacli' circuit nonrcsonant for the current to which its'ringer is responsive, means normally alternating disconnected from said lineand adapted to supply alternating. ringing currents of difl'crcnt 'l'requei'icics, means for connecting any Frequency with the line, and reactive means for preventing current of one frequency .troni opcratively passing througlia ringer intended to be runghy ,dill'c'i'cnt frequency. In a telephone.exchange system, the

conibinalion of a plurality of parallel signaling circuits, means for supplying alternating sigi-ialing currents of (.lill'crcnt fre- -.qucnci.c. s,v each circuitnon rcsonant' lor its allotted ciiri'ei'it,-aiid reactive means for pre- 'venting current of one frequency troni operatively passing through a circuit intended 3;}; ln a telephone exchange system, the combination of a tclcplionc line circuit, a plurality of lclcphoneson said line, a ringer for each telephone, means normally disconnected tron the telephone line at the central cta ti ori 'lor' su'i'il in a'in in" currents of b h D suitable frequencies, a different cqucncy for each ringer, suitable switchi- \(ICVICCS for extending talking connections from calling subscribers to the said telephone line, means for applying the ringing currents through the said switching devices to the telephone line, suitable reactive means including impedance for preventing an opera tive flow of one frequency through the ringer intended to be rung by a different frequency, and branch circuits at least one of which is non-resonant for the ringing current of its allotted substation.

In a telephone exchange system, the combination of a telephone line circuit, a plurality of telephones on said line, a ringer for each telephone, a spring jack for said tele-' phone line, an operators cord circuit pro-' vided with a plug adapted for insertion in said jack, means normally disconnected from the telephone line at the central station for supplying ringing currents of suitable frequencies, a different frequency for each ringer, a selective ringing key by which the operator applies the different ringing currents through the plug and jack to the telephone line, suitable reactive means including capacity for preventing an operative flow of one frequency through the ringer intended to be rung by a difierent frequency, and branch circuits at least one of which is non resonant for the ringing current of its allotted substation.

36. In a telephone exchange system, the combination of a telephone line, a plurality of telephones on said line, a ringer for each telephone, means at the central station for supplying ringing currents of suitable frequencies, a different frequency for each ringer, suitable switching devices for extending talking connections from calling subscribers to the said telephone line, means for applying the ringing currents through the said switching devices to the telephone line, suitable reactive means for preventing an operative flow of one frequency through the ringer intended to be rung by a different frequency, and parallel ringing circuits for said ringers, each ringing circuit being nontuned or non-resonant for frequency by which its allotted ringer can be operated.

37. In a telephone exchange system, the combination of a telephone line, a plurality of telephones (in said line, a ringer for each telephone, a spring jack for said telephone line, an operators cord. circuit provided with a plugadapted for insertion in said jack, means at the central station for supplying ringing currents of suitable frequencies, a different frequency for each ringer, a selective ringing key by which the operator applies the di fferent ringing currents through the plug and jack to the telephone line, suitable reactive means for preventing an operative flow of one frequency through the ringer intended to be rung by a different frequency, and parallel ringing circuits for said ringers, each ringing circuit being nontuned or non-resonant for frequency by which its allotted ringer can be operated.

38. In a telephone exchange system, the combination of a telephone line, a plurality of telephones on said line, a ringer for each telephone, means at the central station for supplying ringing currents of suitable frequencies, a different frequency for each ringer, suitable switching devices for extending talking connections from calling subscribers to the said telephone line, means for applying the ringing currents through the said switching devices to the telephone line, suitable reactive means for preventing an operative flow of one frequency through the ringer intended to be rung by a different frequency, and parallel shunt circuits including said reactive means.

39. In a telephone exchange system, the combination of a telephone line, a plurality of telephones on said line, a ringer for each telephone, a spring jack for said telephone line, an operators cord circuit provided with a plug adapted for insertion in said jack, means at the central stat-ion for supplying ringing currents of suitable frequencles, a different frequency, for each ringer, a selectlve rlngin key by which the operator applies the different ringing cur-, rents through the plug and jack to thetelephone line, suitable reactive means for preventing an operative flow of one frequency through the ringer intended to be rung by a different frequency, and parallel shunt circuits including said reactive means.

' 40. In a telephone exchange system, the combination of a telephone line, a plurality of telephones on said line, a ringer for each telephone, means at the central station for supplying ringing currents of suitable frequencies, a different frequency for each ringer, suitable switching devices for extending talking connections from calling subscribers to thesaid telephone line, means for applying th'iinging currents through the said switching devices to the telephone line,-suitable reactive means for preventing an operative flow of one frequency through the ringer intended to be rung by a different frequency, parallel ringing circuits for said ringers, and parallel shunt circuits including said reactive means, each ringing circuit being non-tuned or non-resonant for frequency by which its allotted ringer can be operated. v

41. In a telephone exchange system, the combination of a telephone line, a plurality of telephones on said line, a ringer foreach telephone, a spring jack for said telephone line, an operators cord' circuit provided with a plug adapted for insertion in said jack, means at the central station for supplying ringing currents of suitable fre quencies, fa different frequency for each ringer, a selective ringing key by which the operator japplie's the diiferent ringing cur- 5 rents through the plug and ack to the telephone line, suitable'reactive means for preventing an operative flow of one frequency through the ringer intended to be r'= .ng by a different frequency, parallel ringing circuits for said ringers, and parallel shunt circuits including said reactive means, each ,ringing circuit being non-tuned or nonringer can be operated.

212 A selective ring ng party line system, comprising a telephone line, a plurality of ringers on said line, a reactive ringing cir- -cuit for one ringer, suitable circuits for the other ringers, means for supplying alter- I Q resonant for freouency by which its allotted hating ringing currents of different fre- ';'quencies, reactive means for preventing cur- 'ren't of the wrong ffrequency from opera tively passing through the ringer having said reactive circuit, said reactive circuit being non-resonantfor the current to which itsallotted ringer is responsive, and suitable provisions {by which the other ringers are also each responsive to their allotted frequency.

3. A selfectitre ringingparty line system comprinsinga, telephone line, a plurality of p, ringers on said line, a branch circuit for the substation; of each ringer, an electromagnetic device allotted to the terminal of said 'line and adapted for use bythe subscriber at any substation thereon in calllng other subscribers, ineans associated with each ringer for controlling the operation of saidelectromagnetic dev ce, a switch termi- 40 nal for extending a talkihg connection to said} line when a subscriber thereon .is called, means for supplying alternating ringing currents of difier'e'nt frequencies through said switch terminal to said line, suitable'reactive means for preventing current ofjon ipassing through the ringer intended to be e s-shy a for cutting ofi said reactive means when 59 tlie subscriber answers the call of his ringer,

i differentfrequency, the high frequency .e. frequency from operatively fferen-t frequency, and means rin er having aipath that is non-res0nant for he current to which it is'rcsponsivc.

*4 In a telephone system, a party line, a plu tlity of ringers "thereon, a branch circuit and telephone for the substation of each ringer, parallel ringing circuits each including but a single branch and ringer,

46. In a telephone system, a party lline, a

plurality of ringers connected with said line, a branch circuit and telephone for the substation of each ringeiymeans for supplying alternating currents of diife rent frequencies, to selectively operate said ringers, each current causing the operation of but a single ringer and reactive means for preventing current of one frequency from operatively passing through the ringer intended to be rung by a diiferent frequency, the low frequency ringer having a path that is nonresonant for the current to which it is responsive.

47. In 'a party-line telephone system, the combination of a telephone line, a plurality of substations located on said line, a branch circuit for each substation, an exchange or central-station, allparty-line subscribers of the exchange being divided into diiferent classes, a plurality o ci'irrent generators located at the exchange or central station, adapted to supply ringing currents of different frequencies, one definite frequency for each distinct class of )arty-line subscribers, means for connecting the requisite generator with the line of any' called partyline subscriber, according to the class to which such called subscriber belongs, ringers at the party-line substations, suitable re active means for preventing current of one frequency from operatively passing through the ringer designed for a different frequency, and-a telephone for each ringer, 10- cated at the different substations on the line, one or more of said branch circuits being non-resonant for the current to which th ringer thereof is responsive I 48. In a party-line telephone system, the combination of 'a telephone line, a pluralit of substations located on said line, eac provided with adifi'erent character of call- 1 signal, but with similar common-battery telephone instruments, a branch circuit for each substationia battery common to all of said telephone instruments, a current generator having'a {certain frequency for operating one of said signals, a current genorator having a different frcquency for operating a signal which is not responsive to used onthe line, by rendering the renews tire means for preventing current of one frequency from operatively passing through the cell-signal designed for a different he quency, one or in ore of said branch. circuits being non-tuned for the current to which its call-signal is responsive.

L The combination of a telephone line, plurality of substations .locatedon said line, a signal for each substation, parallel branch circuits for said signals, means'for supplying ringing currents of suitable frequencies, a different frequency for each sig nal, at least one of said circuits having reactive means associated With the signal thereof to in distinguishing between the different frequencies that are actually said one circuit non-iesonant for the frequency to u'lich its signal. is responsive, and suitable provisions by which the other signals ere equally eiflective in distinguishing between 'aid first-nentioned frequency, and read the different frequencies, whereby each sig nal only responds to its allotted frequency.

50. In a telephone exchange system, the combination of a telephone line, a plurality of subscribers stations on said line, a suitable ringer at each station, means for supplying ringing currents of difierent fre quencies, one different frequency for each ringer, ringing circuits for said ringers, each circuit non-resonant for the current to which its ringer is responsive, and means to prevent current of one frequency from passing through the ringing circuit of a ringer designed for another frequency, to an objectionable degree.

In Witness whereof, I hereunto subscribe my name this 30th day of April A. 1),, 1901.

OSCAR M. LEIGH.

. Witnesses MAXW. ZAnEL, HARVEY L. HnNsoN. 

